Projection-type display devices are generally devices that integrate light sources, optics systems, electronics, and other components for projecting data such as images, video, documents, and spreadsheets from computers or video devices onto walls or front or rear screens, for large-image viewing. They are popular among business users who give presentations as part of their job responsibilities. Newer projectors can weigh as little as a few pounds, making them well suited for business travelers. As the quality of projection technology has improved, projectors are also finding their way into peoples' homes for high-definition television (HDTV) and other applications.
Some projection-type display devices rely on optical or light modulators. A modulator may modulate light in accordance with the pixels of image data, by reflecting, refracting, diffracting, or transmitting the light based on the pixels of the image data. Once the light has been modulated by the modulator, it can be collected by a collector or field lens for ultimate projection by a projection lens outwards from the display device. For optimal image quality, the field lens may have to be nominally the same size as the modulator (e.g., relatively large) and free of aberrations and other defects. The type of field lens used in a projection system, or a projector, can therefore impact the quality and cost of the projection system or projector.